ABSTRACT Polyhydroxyalkanoates [P(HA)s] are accumulated in a number of bacteria as intracellular ... more ABSTRACT Polyhydroxyalkanoates [P(HA)s] are accumulated in a number of bacteria as intracellular carbon and energy storage materials under limited nutrient conditions. P(HA)s have generated significant commercial interest due to their application as biodegradable thermoplastics that can be produced using renewable resources. The use of cheap renewable carbon sources, specially originated from industrial or agricultural by-products, can provide a way to reduce the price. Cheese whey, a by-product of the dairy industry, is available in large amounts from cheese manufacture, also causing disposal problems in EU. We report here the construction of recombinant strains and data related to their growth and polyester accumulation in lactose, hydrolyzed whey and directly in whey permeate, the fraction containing concentrated lactose obtained by ultrafilatration. Cupravidus necator, a gram-negative, facultative chemolithototrophic bacterium, has been intensively investigated for almost 50 years and recently the genome sequence of strain H16 was published. Strain DSM 545, able to produce a range of interesting polymers including polyamides such as cyanophycin, was chosen as the model organism since it is especially known to accumulate high amounts of P(HA)s. However, this strain can not utilize lactose as carbon source, therefore we constructed a genetically modified strain able to use this disaccharide. We described here the introduction of the β-galactosidase gene from Escherichia coli using different plasmids and the insertion of this gene in the chromosome of DSM 545. All the modified strains were able to grow and produce poly-3-hydroxybutyrate directly from lactose, hydrolyzed whey and whey permeate.
The genome sequence ofstrain HCNT1, isolated from root nodules of the legumegrowing in wild stand... more The genome sequence ofstrain HCNT1, isolated from root nodules of the legumegrowing in wild stands in Tuscany, Italy, is described here. Unlike otherstrains, this isolate features a truncated denitrification pathway lacking NO/NO reductase activity and displaying high sensitivity to nitrite under anaerobic conditions.
This paper is a microbiological voyage throughout the main discoveries and research activities of... more This paper is a microbiological voyage throughout the main discoveries and research activities of scholars who studied or taught in this field at Padova University during its 800-year history. The ancient practice of variolization, the so-called miracle of Legnaro and the pellagra debate, whose observations and investigations were driven at Padova even before microbiology was established as a scientific discipline, along with the modern era research activities in the field of agricultural, environmental and food microbiology, undoubtedly suggest the hallmark and everyday role played by microbes in overwhelmingly global, but profoundly human, adventures.
ABSTRACT A study was carried out to assess the behaviour, in terms of strain survival and genetic... more ABSTRACT A study was carried out to assess the behaviour, in terms of strain survival and genetic stability, of genetically modified micro-organisms (GEMs) during their storage in commercial-type agricultural inoculants. Three genetically modified Rhizobium leguminosarum biovar viciae strains were constructed, using a gene cassette containing an inducible lacZ gene from Escherichia coli and mercury resistance determinants from transposon Tn 1831. In the first case the genes have been integrated into the chromosome, the second strain contains the inducible cassette on a plasmid, in the third case the cassette is carried by the same plasmid, but the lacZ is constitutively expressed at high levels, due to the removal of the regulatory structure (lac operator) between the gene and its promoter. Three inoculum formulations, based on liquid, vermiculite and peat carriers, were prepared using the genetically modified strains, and were monitored during a period of up to 16 months. Results indicate a high stability of the chromosomally integrated markers. The plasmid-borne modification also was very stable, though the presence of the plasmid affected the strain growth kinetics. In contrast, the strain containing the highly expressed lacZ showed dramatic marker instability. Strain behaviour in stored inoculant packages reflected that observed in batch cultures; moreover, prolonged storage appeared to magnify differences found in in vitro cultures.
Due to their long domestication time course, many industrial Saccharomyces cerevisiae strains are... more Due to their long domestication time course, many industrial Saccharomyces cerevisiae strains are adopted in numerous processes mostly for historical reasons instead of scientific and technological needs. As such, there is still significant room for improvement for industrial yeast strains relying on yeast biodiversity. This paper strives to regenerate biodiversity with the innovative application of classic genetic methods to already available yeast strains. Extensive sporulation was indeed applied to three different yeast strains, specifically selected for their different origins as well as backgrounds, with the aim of clarifying how new variability was generated. A novel and easy method to obtain mono-spore colonies was specifically developed, and, to reveal the extent of the generated variability, no selection after sporulation was introduced. The obtained progenies were then tested for their growth in defined mediums with high stressor levels. A considerable and strain-specific ...
ABSTRACT Polyhydroxyalkanoates [P(HA)s] are accumulated in a number of bacteria as intracellular ... more ABSTRACT Polyhydroxyalkanoates [P(HA)s] are accumulated in a number of bacteria as intracellular carbon and energy storage materials under limited nutrient conditions. P(HA)s have generated significant commercial interest due to their application as biodegradable thermoplastics that can be produced using renewable resources. The use of cheap renewable carbon sources, specially originated from industrial or agricultural by-products, can provide a way to reduce the price. Cheese whey, a by-product of the dairy industry, is available in large amounts from cheese manufacture, also causing disposal problems in EU. We report here the construction of recombinant strains and data related to their growth and polyester accumulation in lactose, hydrolyzed whey and directly in whey permeate, the fraction containing concentrated lactose obtained by ultrafilatration. Cupravidus necator, a gram-negative, facultative chemolithototrophic bacterium, has been intensively investigated for almost 50 years and recently the genome sequence of strain H16 was published. Strain DSM 545, able to produce a range of interesting polymers including polyamides such as cyanophycin, was chosen as the model organism since it is especially known to accumulate high amounts of P(HA)s. However, this strain can not utilize lactose as carbon source, therefore we constructed a genetically modified strain able to use this disaccharide. We described here the introduction of the β-galactosidase gene from Escherichia coli using different plasmids and the insertion of this gene in the chromosome of DSM 545. All the modified strains were able to grow and produce poly-3-hydroxybutyrate directly from lactose, hydrolyzed whey and whey permeate.
The genome sequence ofstrain HCNT1, isolated from root nodules of the legumegrowing in wild stand... more The genome sequence ofstrain HCNT1, isolated from root nodules of the legumegrowing in wild stands in Tuscany, Italy, is described here. Unlike otherstrains, this isolate features a truncated denitrification pathway lacking NO/NO reductase activity and displaying high sensitivity to nitrite under anaerobic conditions.
This paper is a microbiological voyage throughout the main discoveries and research activities of... more This paper is a microbiological voyage throughout the main discoveries and research activities of scholars who studied or taught in this field at Padova University during its 800-year history. The ancient practice of variolization, the so-called miracle of Legnaro and the pellagra debate, whose observations and investigations were driven at Padova even before microbiology was established as a scientific discipline, along with the modern era research activities in the field of agricultural, environmental and food microbiology, undoubtedly suggest the hallmark and everyday role played by microbes in overwhelmingly global, but profoundly human, adventures.
ABSTRACT A study was carried out to assess the behaviour, in terms of strain survival and genetic... more ABSTRACT A study was carried out to assess the behaviour, in terms of strain survival and genetic stability, of genetically modified micro-organisms (GEMs) during their storage in commercial-type agricultural inoculants. Three genetically modified Rhizobium leguminosarum biovar viciae strains were constructed, using a gene cassette containing an inducible lacZ gene from Escherichia coli and mercury resistance determinants from transposon Tn 1831. In the first case the genes have been integrated into the chromosome, the second strain contains the inducible cassette on a plasmid, in the third case the cassette is carried by the same plasmid, but the lacZ is constitutively expressed at high levels, due to the removal of the regulatory structure (lac operator) between the gene and its promoter. Three inoculum formulations, based on liquid, vermiculite and peat carriers, were prepared using the genetically modified strains, and were monitored during a period of up to 16 months. Results indicate a high stability of the chromosomally integrated markers. The plasmid-borne modification also was very stable, though the presence of the plasmid affected the strain growth kinetics. In contrast, the strain containing the highly expressed lacZ showed dramatic marker instability. Strain behaviour in stored inoculant packages reflected that observed in batch cultures; moreover, prolonged storage appeared to magnify differences found in in vitro cultures.
Due to their long domestication time course, many industrial Saccharomyces cerevisiae strains are... more Due to their long domestication time course, many industrial Saccharomyces cerevisiae strains are adopted in numerous processes mostly for historical reasons instead of scientific and technological needs. As such, there is still significant room for improvement for industrial yeast strains relying on yeast biodiversity. This paper strives to regenerate biodiversity with the innovative application of classic genetic methods to already available yeast strains. Extensive sporulation was indeed applied to three different yeast strains, specifically selected for their different origins as well as backgrounds, with the aim of clarifying how new variability was generated. A novel and easy method to obtain mono-spore colonies was specifically developed, and, to reveal the extent of the generated variability, no selection after sporulation was introduced. The obtained progenies were then tested for their growth in defined mediums with high stressor levels. A considerable and strain-specific ...
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Papers by Marina Basaglia